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Urban Deer Management

Chellby Kilheffer, working with Dr. Brian Underwood (SUNY ESF, USGS), conducted her master's thesis research on urban white-tailed deer. Her thesis research examined green spaces in the Eastside communities of Syracuse, surrounded by Interstates 690, 481, and 81, and their influences on white-tailed deer (Odocoileus virginianus) movements. White-tailed deer populations have increased significantly in the last several decades, particularly in urban areas, and are a concern among local residents and politicians in many urban areas in the northeastern United States. High urban deer densities wreak havoc on natural vegetation cycles, facilitate changes in plant communities (including favoring expansion of non-native/ invasive species), serve as a host for disease-spreading tick species, increase human-wildlife conflicts (i.e., vehicle collisions), and attract predators like coyotes and bears. Management of urban deer is costly and controversial due to the limited non-lethal options available. Mitigation of high urban deer densities can occur through alteration and management of green spaces, which deer rely upon for food and protection. Kilheffer's thesis, "Effects of landscape composition and structure on abundance and distribution of urban white-tailed deer," addresses responses of deer to green spaces in Syracuse, New York.

White-tailed deer were surveyed using distance sampling methods from a vehicle along roadways in Syracuse's Eastside communities in summer and autumn 2013. Surveys routes were randomly chosen to approximately 20-km, covered as much of the study area as

possible, and contained as few close turn-angles as possible to avoid double-counting the same group of deer within a survey. Surveys were conducted in the hour after official sunrise to optimize encounter rates with deer, since they typically exhibit crepuscular behavior. At each deer group encounter, the GPS location, the distance and angle between center of the deer group and vehicle, and age and sex ratios were recorded. Per distance sampling methods, the distance between deer group and roadway, calculated from the distance and angle between deer group and vehicle, were input into Program Distance (http://www.ruwpa.st-and.ac.uk/ distance/). Program Distance calculated deer density and probability of detection.

Digital orthoimagery for Syacuse was classified into land cover using supervised maximum likelihood image classification tools in ArcGIS. Land cover classes included water, trees, shrubs, grass, and impervious surfaces. Accuracy of the classification scheme was assessed using standard methods. Patches of deer habitat were identified using an ArcGIS extension called "PatchMorph", which aggregates pixels of like classification into either habitat or non- habitat based upon user-defined categories. Habitat constituents include food, water, and cover for all wildlife species. For deer, trees and shrubs (i.e., protective cover) were considered important deer habitat for this analysis as food (shrubs and grass) and freshwater were not expected to be limiting for deer in Syracuse.

Forty-three surveys of white-tailed deer, covering approximately 85% of available roadway, were conducted from April 2013 to October 2013. Average deer group size was 2, highest in September and lowest in June. Detection of deer groups was nearly perfect up to approximately 20 km from the roadway. Detections of deer were closely associated with habitat patches identified through PatchMorph.

Average deer density (~4 deer/km2) across the Eastside communities of Syracuse is low relative to other urban areas (> 20 deer/km2). Syracuse's deer population may still be expanding, as its irruption began only a few decades ago (see Van Druff and Rowse 1986). Local deer density is quite high in some portions of the area (i.e., >5 times greater than average). Deer density modeled through habitat covariates was much greater than through distance sampling, which could suggest a bias in population estimates. However, their space use and affinity for green spaces is reliable and compelling. Urban wildlife specialists and designers can use this information, and future work conducted by the authors and several additional collaborators since 2013, to inform green space management in urban areas to mitigate conflicts with white-tailed deer.

Working under the supervision of co-major professors, Dr. Melissa Fierke and Dr. Stephen Shaw, Nick Piedmonte examined how landscape-level percent forest cover and site-level habitat type influenced blacklegged nymph and adult density, and associated tick-borne pathogen prevalence across an urban–rural gradient in an inland Lyme-emergent region of Central New York. Blacklegged ticks (Ixodes scapularis Say) are the most commonly encountered and medically-relevant tick species in New York State, and they have exhibited recent geographic range expansion. Forests and adjacent habitat are important determinants of blacklegged tick density, and may influence prevalence of tick-borne pathogens in resident tick populations. Identifying forest characteristics affecting tick distribution and density will aid in implementing management efforts and assessing entomological risk, particularly in newly invaded areas where their ecological relationships may differ from long endemic regions with substantially higher tick densities. This research is documented in Nick's thesis, "Blacklegged Ticks, Ixodes scapularis Say, in Central New York: Density, Distribution, and Prevalence of Human Pathogens."

Blacklegged tick nymphs and adults were collected using standardized tick drags at 16 sites throughout Onondaga County, N.Y. in summer and fall 2015 and 2016. Sites were chosen to reflect a landscape cover gradient ranging from urban to rural to investigate a spectrum of forest cover from relatively small fragments to contiguous forest. This urban–rural gradient permitted analysis of tick distribution and density extending beyond typical homogenous suburban environments commonly targeted in studies conducted in southeastern N.Y. Small-scale landscape features were characterized as "edge" and "wooded" habitat. Wooded habitat consisted of areas with leaf litter and nearly complete tree canopy coverage, while edge habitat was defined as the immediate interface between wooded and maintained grassy areas such that an investigator stood in maintained lawn space extending the drag into herbaceous plants, long grasses, and shrubs along the forest's edge. ArcGIS and an NLCD 2011 U.S. Forest Service canopy cover raster data set were used to quantify percent forest cover at multiple spatial scales using buffers around sampling points to tabulate quantity of forested area around each site. Generalized linear mixed models were used to statistically assess relationships among landscape features, tick density, and pathogen prevalence.

Higher tick densities in urban and suburban parks, relative to rural parks, is important to recognize as many may consider themselves less susceptible to ticks in urbanized areas. Possible biological mechanisms underlying tick distribution among habitats include host habitat use and seasonal movement patterns, and differences in robustness of nymphs versus adult blacklegged ticks. Important hosts, such as white-tailed deer and white-footed mice, exhibit seasonal movement patterns corresponding with patterns of nymph and adult tick densities between forest edge and interior. Adults are also considered physiologically more robust than nymphs, and are capable of climbing higher on vegetation and withstanding greater desiccation than nymphs. These factors alone or in combination are likely contributing to within-site tick distributions.

Blood-feeding Blacklegged Tick developmental stages

In collaboration with the NYS Department of Health, a subset of blacklegged ticks collected from each site and habitat were individually evaluated by real-time polymerase chain reaction for the presence of 5 known etiological agents of human disease carried by blacklegged ticks including: Lyme disease (Borrelia burgdorferi), B. miyamotoi infection (B. miyamotoi), human granulocytic anaplasmosis (Anaplasma phagocytophilum), human babesiosis (Babesia microti), and Powassan encephalitis (deer tick virus). Borrelia burgdorferi prevalence was greater than all other pathogens investigated, ranging from 0.0–31.4% in nymphs (13.0 ± 1.8%) and 0.0–79.2% in adults (44.8 ± 3.1%) among sites and between years. Anaplasma phagocytophilum prevalence was low in comparison to B. burgdorferi, ranging from 0.0–12.0% in nymphs (1.4 ± 0.6%) and from 0.0–6.0% in adults (1.2 ± 0.3%) among sites and between years. Borrelia miyamotoi prevalence was also low, ranging from 0.0–3.2% (0.2 ± 0.1%) in nymphs, and from 0.0–4.0% (0.9 ± 0.2%) in adults. Co-infection was a rare occurrence across all sites and pathogens, but more commonly observed in adults.

Borrelia burgdorferi prevalence was, on average, 3.4 times higher in adults compared to nymphs, while prevalence of A. phagocytophilum and B. miyamotoi were similar between developmental stages. Dominant land use (i.e. urban vs. rural) had no effect on B. burgdorferi prevalence. While statistical analyses were limited by low overall prevalence of A. phagocytophilum and B. miyamotoi, an effect of dominant land use was still apparent with ~ 95% of A. phagocytophilum and 83% of B. miyamotoi positive ticks collected in urban sites, while only ~ 5% and ~ 17%, respectively, were collected in rural environments. No obvious patterns between habitats or years was present for any pathogen investigated. Babesia microti and deer tick virus were not detected in ticks collected from any site.

The true leading edge of increasing blacklegged tick-borne disease is currently thought to lie somewhere within the 150 km interval between Rochester and Syracuse, N.Y. While Onondaga County certainly lies near this leading edge, B. burgdorferi prevalence was surprisingly similar to, if not greater than that documented in eastern and southeastern N.Y. counties with long histories of endemicity. Borrelia burgdorferi prevalence was significantly higher in adults than in nymphs. This phenomenon is common, and caused by the additional opportunity adults have to imbibe pathogens during the second blood meal. Collection of a majority of ticks infected with A. phagocytophilum or B. miyamotoi from urban versus rural sites may be attributable to correspondingly higher densities of certain competent reservoir species in urban and suburban environments.

Synanthropic reservoir species, such as white-footed mice and American robins, experience uncharacteristically high densities in urban areas. Smaller forest stands in these areas could increase tick host acquisition success, and thus pathogen acquisition, because ticks and their wildlife hosts are forced into a smaller area of forested habitat compared to contiguous rural stands. Common operation of bird feeders in suburban neighborhoods may also contribute to artificially elevated reservoir species abundance, and it has been documented as contributing to increased domestic entomological risk and Lyme disease incidence. The combination of these factors could act to amplify tick survival and development and sylvatic pathogen cycling in urban and suburban environments. Subsequent host and tick movement between suburban and rural areas could be contributing to tick and pathogen geographic range expansion. In this way, urban and suburban areas may represent a sort of oasis for ticks and tick-borne pathogens from which they may then disperse to and colonize more rural areas.

Toby Liss wants to know if novel assemblages of marginal plant species can enhance green roof function. She is working with her major professor, Dr. Don Leopold, to investigate this question in her dissertation research. The answer may lie in "marginal" plant habitat, sites where drought, intense sun, wind stress, and shallow, rocky, infertile soils exist. The significance of this research is that it could improve the function of green roofs as a tool for stormwater management.

Stormwater runoff from impervious surfaces is a major environmental challenge, and green roofs are one way to manage this problem. However, the species commonly grown on green roofs do not maximize the removal of stormwater. Stresses from dry conditions, sun, wind, and infertile soil limit the range of plant species that can be grown on green roofs, but similar plant habitats exist in nature. Far from being barren wastelands, these stressed habitats actually support rare and highly diverse groupings of plants.

Using diverse plantings of extremely resilient species will likely improve green roof aesthetics and function. Eliminating stormwater runoff by retaining it in the soil and returning it to the atmosphere through plants (evapotranspiration) is a key function of green roofs that can reduce the damages associated with excessive stormwater runoff, making urban landscapes more sustainable. In her research, Toby is investigating whether novel combinations of marginal plant species can create measurable improvements in green roof stormwater performance over industry standard practices. She has done preliminary experiments to identify additional species that will grow well on green roofs, and she is developing experiments that will test whether increased diversity of species will improve stormwater elimination via evapotranspiration on green roofs. Toby hopes to use her results to help designers make the informed plant selections when they build green roofs. Stay tuned!

Community resident, Karen Loftin, was a key member of the survey team.

At the October 2017 American Collegiate Schools of Planning conference in Denver, Ph.D. student Yi Wang and MLA student Shagha Shahhosseini, together with Dr. Margaret Bryant, presented findings from the Syracuse Neighborhood Health Study. The work was titled, "Land Use Patterns and Resident Perspectives in a Neighborhood of Concentrated Poverty: Implications for Health and Physical Activity Interventions." (Link to poster)

Syracuse, New York has the dubious distinction of having the highest level of poverty concentration for black and Hispanic residents among the nation's 100 largest metropolitan areas (Jargowsky, 2015). This study examined one of the poorest neighborhoods in Syracuse, the Southwest neighborhood, using a fine-scale analysis of urban form coupled with detailed survey data about resident health status, health behaviors, and neighborhood perception. The study sought to understand the relationship between physical conditions in the neighborhood and resident perceptions and behaviors that might support, or detract from, neighborhood-based physical activity interventions such as walking programs.

The methodology was comprised of two parts: an analysis of physical conditions using GIS and an in-person randomized survey. The team used stratified random sampling of 121 addresses in the Southwest neighborhood, and conducted a survey of 121 residents ages 40 and above (response rate of 38%). To be as inclusive as possible, surveys were conducted in participants' homes. Study teams were comprised of one graduate student and one community member, like Karen Lofton, pictured above. Participants received a $20 gift card for taking the survey.

This study revealed characteristics common to disadvantaged neighborhoods: fragmented urban form with high numbers of vacant lots and vacant buildings; absentee landowners and a high percentage of renter-occupied housing; a high poverty rate; and a high crime rate in the context of the city as a whole. The in-person randomized survey, conducted with 121 neighborhood residents aged 40 or older, revealed health characteristics commonly associated with residents of disadvantaged neighborhoods [e.g., high rates of self-reported diabetes]. However, the survey results also challenged the idea that the neighborhood was not a good place to live [e.g., high levels (71%) of neighborhood satisfaction].

Yi Wang and Shagha Shahhosseini at the ACSP conference

Related to outdoor physical activity, the majority of respondents reported, for example, that they see people being physically active in the neighborhood, think that it is safe to walk through the neighborhood during the day in spite of the perception that the neighborhood has a high crime rate, and recognize many or most adults that they see in the neighborhood. Health status and health behavior survey results suggest that public health interventions, like diabetes prevention programs, are needed in the neighborhood.

The results also indicate that health interventions can be designed to take advantage of high social capital, cohesion, and overall positive associations with the neighborhood from residents who have lived there, in many cases, for decades. The neighborhood may be among the nation's most challenged, as indicated by levels of concentrated poverty and associated physical conditions, but the neighborhood also has positive characteristics that can provide a foundation for neighborhood-based physical activity programs. Urban planning interventions can similarly respond to, and build upon, the strong sense of community that can remain in even the most challenged neighborhoods.

Jargowsky, Paul. 2015. Architecture of segregation: Civil unrest, the concentration of poverty, and public policy. New York: The Century Foundation.